Key information relevant to the recruitment process for the
overall study, such as dates of the recruitment period and locations

This study was conducted at 29 active centers in 10 countries (10 centers in Germany, 5 centers in the United States of America [USA], 3 centers in France, 2 centers in Australia, Czech Republic, Italy, and Israel, and 1 center in Greece, Taiwan and United Kingdom [UK])

Pre-Assignment Details

Significant events and approaches for the overall study
following participant enrollment, but prior to group assignment

Participants were on bosentan therapy for 3 months prior. Participants were randomized to sildenafil or placebo. Part A study was double-blind phase (12 weeks) and Part B was 12 months open-label phase. 53 and 51 participants were randomized to placebo and sildenafil arm respectively. One participant in sildenafil arm did not receive any treatment

Reporting Groups

Description

Placebo

In Part A of the study: the participants received placebo three times a day (TID), in addition to their existing stable bosentan treatment (62.5 mg BID or 125 mg BID for minimum 3 months prior to randomization), for 12-Week Double-Blind Phase of the study.

In Part B of the study: All the participants received sildenafil 20 mg TID for 12 months.

Sildenafil

In Part A of the study: the participants received sildenafil 20 mg TID, in addition to their existing stable bosentan treatment (62.5 mg BID or 125 mg BID for minimum 3 months prior to randomization), for 12-Week Double-Blind Phase of the study.

In Part B of the study: All the participants received sildenafil 20 mg TID for 12 months.

Explanation of how the number of participants for analysis was determined.
Includes whether analysis was per protocol, intention to treat, or another method.
Also provides relevant details such as imputation technique, as appropriate.

No text entered.

Reporting Groups

Description

Placebo

In Part A of the study: the participants received placebo three times a day (TID), in addition to their existing stable bosentan treatment (62.5 mg BID or 125 mg BID for minimum 3 months prior to randomization), for 12-Week Double-Blind Phase of the study.

In Part B of the study: All the participants received sildenafil 20 mg TID for 12 months

Sildenafil

In Part A of the study: the participants received sildenafil 20 mg TID, in addition to their existing stable bosentan treatment (62.5 mg BID or 125 mg BID for minimum 3 months prior to randomization), for 12-Week Double-Blind Phase of the study.

In Part B of the study: All the participants received sildenafil 20 mg TID for 12 months.

6MWT is the distance that a participant could walk in 6 minutes. Participants were asked to perform the test at a pace that was comfortable to them, with as many breaks as they needed. Continuous pulse oximetry was conducted during the test for safety.

Principal Investigators are NOT employed by the organization sponsoring the study.

There IS an agreement between Principal Investigators and the Sponsor (or its agents) that restricts
the PI's rights to discuss or publish trial results after the trial is completed.

The agreement is:

The only disclosure restriction on the PI is that the sponsor can review results communications prior to public release
and can embargo communications regarding trial results for a period that is less than or equal to 60 days.
The sponsor cannot require changes to the communication and cannot extend the embargo.

The only disclosure restriction on the PI is that the sponsor can review results communications prior to public release
and can embargo communications regarding trial results for a period that is more than 60 days but less than
or equal to 180 days. The sponsor cannot require changes to the communication and cannot extend the embargo.

Other disclosure agreement that restricts the right of the PI to discuss or publish trial results after the trial is completed.

Restriction Description:
Pfizer has the right to review disclosures, requesting a delay of less than 60 days. Investigator will postpone single center publications until after disclosure of pooled data (all sites), less than 12 months from study completion/termination at all participating sites. Investigator may not disclose previously undisclosed confidential information other than study results.